Polysiloxanes having vinyl or epoxy functionality. The polysiloxanes are used to form polymer-based materials having properties particularly suited for biomedical device applications. The polysiloxanes are of general formula I: wherein R is a C2-10 alkenyl, a C2-10 alkyl with an epoxy group or a C5-C7cycloalkyl with an epoxy group; R2, R3 and R4 are each independently selected from the group consisting of hydrogen, C1-4 alkyl, C1-4 fluoroalkyl, optionally substituted phenyl and optionally substituted benzyl; A is —OH or —NHR5, wherein R5 is hydrogen or a C1-3 alkyl; and B is —R1-A or —R6, wherein R1 is a linking group having an alkylene group with 2 to 8 carbon atoms wherein the alkylene group optionally includes ether, urethane or ureido linkages; and R6 is selected from the group consisting of C1-4 alkyl, optionally substituted phenyl or optionally substituted benzyl; and m and n are integers with an m:n ratio from 30:1 to 3:1.